Indian input! The Weekly Report of China Disease Control and Prevention disclosed the details of the first detection of the "invisible" Omilon mutant strain

On the evening of January 3, the Chinese Center for Disease Control and Prevention Weekly (English) published an online article revealing the specific situation of the "invisible" Omicron variant detected for the first time in China.

According to the Weekly, on December 19, 2021, a 31-year-old man boarded a flight from Bhubaneswar, India, to Mumbai, India, and then from Mumbai to Muscat, Oman. On December 24, he flew back to Guangzhou from Muscat and was transferred to a centralized quarantine hotel in Foshan. He received nucleic acid sampling on the third day of isolation and tested positive for nucleic acid on December 27, 2021. On the same day, the case was sent by negative pressure ambulance to the Eighth People's Hospital of Guangzhou For isolation and treatment. Local inflammation of both lungs is found on chest CT.

On December 28, 2021, the Guangdong Provincial Center for Disease Control and Prevention sequenced nasal swab specimens of imported cases. On December 29, 2021, sequencing analysis concluded that the virus genome belongs to the BA.2 lineage and is an Opmi-Kron variant. Compared with the Wuhan reference sequence, the case strain showed 67 nucleotide mutation sites. The sequences reported on the evolutionary branch are most similar to those reported in Singapore on 20 December 2021 and in Australia on 1 December 2021. At the protein level, a total of 49 amino acid mutation sites and 9 amino acid deletions were observed, of which 27 mutations and 3 deletions of spinous proteins were observed.

On November 26, 2021, the Omikeron variant was listed by the World Health Organization (WHO) as the fifth "strain to be concerned." Studies have shown that the Omiljung variant has evolved into three lineages, namely BA.1, BA.2 and BA.3, of which the BA.1 lineage is the most popular. The BA.2 lineage, informally known as the "invisible Olmiqueron," differs from the "standard" variety and lacks a special genetic variant. The Global Influenza Data Sharing Initiative (GISAID) uploaded 89 BA.2 sequences, most of which came from Countries such as South Africa, Denmark, Canada, the United Kingdom, the United States, and India. The earliest BA.2 sequence was uploaded in South Africa on November 27, 2021.

The Weekly pointed out that the case was the first BA.2 spectrum patient found in China. Due to genomic differences in the BA.2 lineage, its biological properties and rate of transmission may vary, so further studies and long-term monitoring are needed.